Numerous techniques for depositing a variety of coating materials upon the surface of glass substrates, for the purpose of strengthening or reinforcing their surfaces or providing such surfaces with improved optical and/or electrical properties, have been set forth in the prior art. For example, French Patent Application no. 2,542,636 discloses a glass substrate coated with a dielectric layer of tin oxide overlayed with a coating comprising the pyrolysis products produced by the interaction of a metal-based powder and the heated substrate.
One coating technique which has previously been utilized to deposit coatings onto the surface of materials other than glass is known as plasma deposition. The method entails introducing the material to be coated into a reaction chamber provided with a low-energy electrical field. This technique has been used, as described in French Patent Application no. 2,535,650, to deposit a siloxane polymer on a flexible plastic film which has first been coated with a series of thin metal layers. This process results in the production of a flexible insulating material which is thereafter applied to a rigid support, such as a pane of glass, the production and shaping of which having already been completed.
This technique, i.e., plasma deposition, has, however, not been previously used in the field of glass manufacture to form coating layers exhibiting improved abrasion resistance and having improved optical properties directly upon the glass or upon pre-coated glass substrates, when the coated product must subsequently undergo standard processing treatments, i.e., bending, tempering, etc.